Telegraph relay



Oct, 22. 0- R. E. H. CARPENTER 2,219,222

TELEGRAPH RELAY Filed Sept 7, 1937 2 Sheets-Sheet l INVENTOR A TTORNE Y Oct. 22. 1940.

R. E. CARPENTER 2,219,222

' TELEGRAPH RELAY Filed Sept. 7, 1937 2 Sheets-Shae; 2

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Giff/- M 574 4 a). M

Patented Oct. 22, 1940 UNITED STATES PATENT OFFlCE Application September 7, 1937, Serial No. 162,785 In Great Britain September 11, 1936 11 Claims.

This invention relates to telegraph relays and is particularly concerned with the mounting of the contacts of such relays, and with the adjustment and operation of the same.

The objects of the invention are to prevent or reduce chattering between the electrical contacts of telegraph relays when they are brought abruptly into contact with one another, and also to reduce the transit time of a telegraph relay, that is to say, the time elapsing between the moving contact or tongue breaking with one of the side contacts and making with the other.

According to the present invention, one or more of the contacts of a telegraph relay are mounted compliantly so that the sum of the lengths of the gaps between the moving tongue and the side contacts varies and does not remain substantially constant as in the usual form of relay, while the compliance of the contact or contacts is so chosen that with the armature operating forces available, the contacts yield to a sufficient extent to take up practically the whole of the desired travel of the armature. Preferably, such a relay, in which the sum of the lengths of the gaps between the contacts varies is arranged so that the compliance of the contact or contacts is accompanied with heavy damping. This prevents rebound when the contacts come together, and provides other advantages which will be set out in detail so bBlOW.

By employing the invention, it follows that by careful adjustment, which may, however, be easily made and maintained, the transit time of the relay may be made vanishingly small, that is to say so that the armature contact or moving tongue breaks with one side contact practically simultaneously with making with the other side contact. At the same time it is not essential to operate the relay with such an adjustment which provides the possibility of a short circuit between the side contacts of infinitesimal duration at each swing of the armature since the relay may be still made to work very satisfactorily when sufiicient gap is left to prevent this short circuit. It is found in practice, however, that in the great majority of telegraph circuits such a short circuit of brief duration is of no importance since protective resistances are ordinarily connected in the leads to both side contacts and the duration of the short circuit is much too small to enable appreciable short circuit current to be set up.

The novel mounting of the one or more relay contacts introduces a further important advantage consisting in the fact that under conditions 5 when the line current is tending to fail, as may occur for example on leaky land lines, the armature travel is automatically reduced and the relay allowed togo on working without adjustment. With the novel relay, large operating currents merely increase the contact gap on either side 5 available for breaking the output current.

The provision of damping, and preferably heavy damping in association with the compliance is of importance since without it, the armature and its contact would continue to vibrate at the end of 10 each stroke and the phase relation of this vibration with the subsequent reversing current would introduce a variable time lag into the operation of the relay.

Although a compliant mounting of the side 15 contacts has been particularly referred to, the principle of the invention may also be carried into effect by dividing the contact carried by the armature into two parts and mounting each part compliantly, but in such an arrangement it is obviously essential to arrange that each half of the contact has the requisite compliance with respect to the other half, and not merely with respect to the armature proper.

A form of construction of relay contact in which the armature contact is divided and carried on a pair of springs whose ends rub together has been adopted to prevent or reduce bouncing of the armature, but in such previous constructions the compliance of the springs employed has deliberately been made too low to permit substantial variation of the total contact gap with the force normally available in the armature, so that this form of construction does not enable the user to adjust the relay so as to work with vanishingly small transit time. Moreover, this type of construction is liable to exhibit the very undesirable characteristic of hysteresis.

In carrying the invention into effect, it is desirable to employ a design of relay in which the moment of inertia of the armature is low in proportion to the moment of the magnetic forces, due to the signalling currents, acting on it. The desirability of this may be explained as follows. The stiifness of the compliant mountings of the side contacts has to be chosen so as to permit the desired movement of the armature under the signalling current forces available. In this connection, it must be remembered that the effective stifiness is the algebraic sum of the positive stiff- 50 mass of the springs and the negative stillness due to the field flux of the relay. Now the acceleration of the armature toward the central position on the cessation of a signalling current will clearly be determined by this effective stiffness and the moment of inertia of the armature, and it is obviously necessary if the relay is to work at high that this acceleration should be great. For this reason it is particularly advantageous to apply the present invention to a relay of the type described in my prior British Specification No. 315,496.

In order that the invention may be clearly understood and readily carried into effect some forms of construction in accordance with it will now be described with reference to the accompanying drawings, in which:

Figure l is a side elevation of the upper part of a permanent magnet relay with the contacts mounted according to the invention;

Figure 2 is a side elevation to an enlarged scale showing the contact support in central section;

Figure 3 is an end elevation seen from the left of Figure 2; and

Figure 4 is a detail section on the line IV-IV in Figure 3;

Figure 5 is an explanatory diagram of connections;

Figure dis a side elevation; and

Figure '7 an end elevation showing a somewhat modified construction of side contact according to the invention; and

Figure 8 is a side elevation, with the contact support in central section, of yet another form of construction of the novel contact mounting.

Referring first to Figures 1 to 4;, in Figure 1 the permanent magnets are shown at l, with the centre limb at 2 and the swinging armature at hinged to the member 2 by a short spring 4. The armature 3 carries on its opposite faces contact members 5 which may be pieces of platinum, in the usual way.

The side contacts are mounted on adjusting screws 6 which can be locked in pillars l as usual, but the heads of the screws bear shallow, saucerlike members .8, and the'contacts 9, which may also be of platinum, are mounted on flat springs is, each being riveted to the rim of the saucer 8 at one end at H and bearing on the rim of the saucer at the other end i2. As can be seen in Figure 4, the spring at the end I? has a set at the middle so that only its two outer ends i3 bear on the rim of the saucer 8, but sufliciently to give a good initial frictional contact. The spring H3 is of similar cross-section at the other end where it is riveted to the saucer.

The contact supports, consisting of the springs ii) are yielding, and the compliance is so chosen that with the normal armature operating force available, they can yield sufiiciently to absorb practically the whole of the desired travel of the armature. The compliance of the springs I is so chosen that with the operating forces normally available from the armature, a deflection of the order of say, 0.0005 to 0.002 inch is produced. The saucer 8 is shallow so that the spring 10 cannot be permanently deformed either by extraordinary force exerted by the armature 3, or by careless screwing up of the contacts, the inner wall of the bottom of the saucer limiting the amount by which the spring Hi can be bent. As the contact is pressed in, the spring It at the points i3 drags over th rim of the saucer 3, providing the desired heavy damping.

In setting the contacts, the following procedure may be adopted. The bias adjusting means, if fitted, having been set centrally, both side contacts are screwed back until the tongue will rest on either of them. That side contact on which the tongue is in fact resting is then screwed forward very slowly until the tongue is just tripped over to the other side. The said side contact is then retracted very slightly. The second side contact is now screwed forward until both side contacts touch the tongue simultaneously. The second contact may then be moved back until this condition just ceases. A final slight readjustment of the positons of both contacts, in order to leave the bias of the relay neutral, may sometimes then be necessary or a slight readjustment of their relative positions so as to secure a vanishingly small time of simultaneous contact or a small finite transit time may be made as desired. As may be appreciated from Figure 5, for a very short time during each swing, the armature contacts will short-circuit the side contacts 9, no appreciable short-circuit current is set up owing to the brief time of short circuit. Moreover, limiting resistances l4 may be included in the leads to both side contacts 9. Otherwise, Figure shows theusual form of connection with the potential source l5 connected across two resistances of equal value [6 to provide a neutral potential point it. The load, such asateleprinter, isconnected to the leads, l8 whichrun fromthe neutral point Hand the armature contacts .5. When the armature 3 moves to the left, the upper lead I8 receives a positive potential with. respect to the point l1, and when the armature 3 swings to the right the upper lead, [8. receives a negative impulse.

In Figures 6 and 7 a slightly different form of side contact is'illustratedl The head of the adjusting screw 6. now consists of arectangular pieceof metal i9, and the spring l0, corresponding to the spring. Iii in Figures 1 to 4, is now bowed outwardly, being riveted at H to the upper part of the metal block i9, and at the end l2 bearing against the surface of the block l9so as to produce the desired heavy damping when the side contact 5 yields.

Yet another form of construction is shown in Figure 8, where the head of the adjusting screw 6 is in the form of ametal saucer 8;which is'closed by a sheet of fine gauze 26,, clamped around the rim of the saucer. Nevertheless, the gauze may be securedv to the rim by riveting, spot welding, or even by soldering. The gauze, 2,0;bears, the. side contact 9 at its centre, and undue deflection of the gauze is prevented by a stop 2| standing upfrom the middle of the bottom of the. saucer. In this case the compliance is, chosen as; already def scribed, but the damping is inherent in the gauze itself, probably caused by the crossed wires of the gauze sliding slightly on one another when the gauze is pushed in.

In the accompanying claims, the term frictional damping means is to;be interpreted broadly to cover any means of damping involving the dissipation of energy, and it is withinthe scope of my invention to substitute damping by a viscous fluid for the form of damping shown and described herein.

I claim: l I l 1. In an electrical telegraph relay: having a rapidly vibrating armature normally subject to chattering, the combination of a pair of cupshaped contact supports; a pair of metal gauze pieces supported respectively on the rims of said supports, and a pair of contact elements, mounted respectively on said pieces whereby said gauze pieces serve as resilient supports for said contact elements, and an armature mounted for toand-fro movement between said contact'pieces,

said gauze pieces having sufficient compliance to permit movement of said contact pieces under the force exerted by said armature and having sufficient friction developed between the crossed strands thereof during such movement to prevent free vibration of said contacts.

2. A telegraph relay comprising a movable armature mounted for to-and-fro movement, a pair of contact supports mounted on opposite sides of said armature, a plate-like spring element mounted upon each of said supports, each of said spring elements being secured at one end to its support and the opposite end thereof having'resilient frictional engagement with its support, the intermediate portions of each spring element being unsupported, a contact element mounted on an intermediate portion of each of said spring elements and arranged to cooperate with said movable armature whereby upon engagement of said armature with either of said contact elements the associated spring element is flexed and its free end slides longitudinally over the surface of said support at increased contact pressure.

3. In a telegraph relay, the combination of a movable armature having a contact mounted thereon, a contact support mounted in the path of movement of said contact, a plate-like spring element mounted upon said support in a plane transverse to the movement of the contact on said armature and being supported at one end upon said support and the opposite end thereof having resilient frictional engagement with said support, the intermediate portions of said spring element being unsupported, and a contact element mounted upon an intermediate portion of said spring element and arranged to be engaged by the contact on said armature, whereby flexing of said spring element by said armature causes the free end of said spring element to move longitudinally over the surface of said fixed support at increased contact puressure.

4. In an electrical telegraph relay for repeating signals of variable duration, the combination of two spaced contact elements, a movable armature mounted'for substantially aperiodic to-andfro movement between said spaced contacts, two further contact elements mounted upon said armature and allocated respectively to said spaced contacts and arranged to engage said spaced contacts alternatively as said armature is moved first in one direction and then in the other, thereby forming two pairs of cooperating contacts, resilient mounting means for at least one contact in each pair of cooperating contact elements operative during the movements of said armature unit to cause the sum of the lengths of the two gaps formed between the contacts of said two pairs of contacts to vary, said resilient mounting means for each contact comprising a plate-like spring member secured at one end to a supporting member and. having the opposite end thereof in resilient and frictional engagement with said support while the intermediate portions thereof are unsupported, said contacts being mounted on intermediate portions of said spring elements whereby upon being engaged by the cooperating contacts, the spring element of the engaged contact is flexed by said armature and the free end thereof is caused to frictionally slide over the surface of the supporting element under increased contact pressure.

5. A telegraph relay comprising a movable armature mounted for to-and-fro movement, a pair of shallow cup-like supports mounted on opposite sides of said armature and having their open sides facing each other and arranged substantially parallel to said armature, a plate-like spring element arranged across the open side of each cup-like support, each spring element being secured at one end to the annular face of its cuplike support and the opposite end thereof having resilient frictional engagement with another portion of said annular face, a contact element mounted substantially at the center of each spring element and arranged to be engaged by said armature, whereby upon engagement of said armature with either of said contact elements the associated spring element is flexed and its free end is caused to slide over the annular face of its supporting element at increased contact pressure.

6. A telegraph relay comprising a movable armature mounted for to-and-fro movement, a pair of spaced contacts mounted on opposite sides of said armature, a resilient mounting for each of said contacts permitting yielding of each contact when engaged by said armature in the operation of said relay, and frictional damping means for damping the movement of each of said resiliently mounted contacts, each of said damping means comprising two relatively movable elements having frictional contact with each other, and at least one of said elements being movable by the movement of the associated resiliently mounted contact to produce relative sliding movement between said two elements at the point of frictional contact therebetween.

'7. A telegraph relay according to claim 6 in which said spaced contacts are so positioned that there is insufficient free travel of the armature between said spaced contacts to interrupt current in a circuit completed between said armature and either contact, but further movement of the armature against the compliance action of one of said contacts is sufi'icient to interrupt the current between the armature and the opposite contact.

8. A telegraph relay comprising a movable armature mounted for to-and-fro movement, a pair of spaced contacts mounted on opposite sides of said armature, a resilient mounting for each of said contacts permitting yielding of each contact when engaged by said armature in the operation of said relay, and frictional damping means for damping the movement of each of said resiliently mounted contacts, each of said damping means comprising two relatively movable elements having a frictional connection therebetween and being effective to resist movement of the associated contact substantially throughout the extent of the yielding movement of the associated contact, said spaced contacts being so positioned that there is insufficient free travel of the armature between said spaced contacts to interrupt current in a circuit completed between said armature and either contact, but further movement of the armature against the compliance action of one of said resiliently mounted contacts is sumcient to interrupt the current between the armature and the opposite contact.

9. A telegraph relay according to claim 8 wherein practically the whole of the desired travel of the armature on either side of its neutral position is against the compliance of the resilient mounting of one of said contacts, and wherein the operating forces normally available for operating said armature are suficient to produce a deflection of said resiliently mounted contact of the order of 0.0005 to 0.002 inch.

10. A telegraph relay comprising, a movable armature mounted for to-and-fro movement, two

spaced contact. elements mounted on opposite sides of said armature,.two furthercontactelements mounted upon said armature and allocated respectively to saidspaced contacts and arranged to engage said spaced contacts alternately'as said armature is moved first in' one direction and then in the other, thereby forming'two pairs of cooperating contacts, a resilient mounting for at least one Contact in each pair of cooperating c'ontactelements, said resilient mountings permitting yielding of each resiliently mountedjcont'actf by movement of' said armature in the operation of said relay, and frictional damping means individual to each resiliently mounted contact for damping the movement of each ofsaid resiliently mounted contacts, each of said damping'means' comprising two relatively movable elementsihaving frictional contact with each' other; and at least one of said elements being movable by the movement of the associatedresiliently mounted contactto' produce relative sliding movement be tween said two elements at the point of friction-a1 contact therebetween.

11; A telegraph relayaccording to claim 10 in which the cooperating contacts are so positioned thatthere is insufiicient free travel of the armature'to interrupt current in a circuit completed between the contacts of one pair of cooperating contactsrlout further movement of the armature against the compliance action of the resiliently mounted contact inthe other pair of. cooperating contacts is sufiicient to interrupt the current between the contacts of the first pair of cooperating contacts.

RUPERT EVAN HOWARD CARPENTER. 

